In message , Philip Eden
writes
"Graham P Davis" wrote :
STUART ONYECHE wrote:

Is the latest rainfall event really unprescedented? Particularly
interested in whether there have been similar summer events in terms of
both spatial area of rainfall combined with magnitude of the rain. Media/
politicians are too keen to add recent events to the GW bandwagon,
conveniently ignoring the point that with GW our summers are supposed to
get drier, as far as I understand it. I thought the extreme rain events
would be autumn/winter synoptic scale events such as those in 2000, not
summer synoptic scale. Attributing the latest events also to GW makes me
increasingly lose faith in the GW science.


Yes, GW is forecast to give us drier summers, but that is because there
will
be fewer rainfall events in summer. However, single rainfall events are
likely to be heavier due to the increased warmth.

Although having said that -- and I offer this as an observation only, and
not as evidence of anything else -- this summer's individual rainfall events
all have several precedents, whereas the aggregate rainfall for May,
June and July, averaged over England and Wales, has easily broken
the previous record.

It's also worth noting that the synoptic character of MJJ combined
has also been unprecedentedly cyclonic, and there is a strong
correlation between cyclonicity and aggregate rainfall. So the question
I would ask is, "where has that extreme cyclonicity come from?" Not
"where has all the rain come from?"

Philip

No doubt there is somewhere, either upstream or downstream of us or
both, where there has been extreme anticyclonicity during the same
period - though I haven't checked that. If I'm correct, the question
becomes the even broader one of "why has the northern hemisphere
circulation been so anomalous?"

Taking an even wider view, if we factor in the extreme cold weather
events in South America, South Africa and Australia in recent weeks
perhaps the whole global circulation has been notably anomalous. If so,
that might be a direct result of global warming or it might not.

Isn't it a fascinating science.

Norman.
(delete "thisbit" twice to e-mail)
--
Norman Lynagh Weather Consultancy
Chalfont St Giles 85m a.s.l.
England